1,721,014 research outputs found
On the Relationship between Heat Exchanges and Temperature of Bodies at Thermal Equilibrium
Full text linkThe paper refers first to the definition of heat prevalent in thermodynamics. The problem of the temperature and of the exchanges of heat in the bodies at thermal equilibrium is then addressed, providing a new point of view based on the principle of mobile equilibrium
Plasma electrolytic oxidation of Ti - W surface alloys synthetized by PVD-LEHCEB
Full text linkAn innovative approach exploiting PVD-coupled Low-Energy High-Current Electron Beam (LEHCEB) and Plasma Electrolytic Oxidation (PEO) techniques were investigated to obtain photoactive TiO2-WO3 mixed films. Ti-W surface alloys containing 14 at.% W were synthetized by PVD deposition of 185 nm thick W films onto Ti substrates, followed by LEHCEB alloying at 30 kV for 50 pulses. The obtained Ti-W surface alloys were treated by PEO in 1.5 M H2SO4 at constant cell voltage ranging from 100 to 200 V. The resulting mixed oxide films were investigated by XRD, SEM and EDS analysis. Photoelectrochemical properties were determined by linear sweep voltammetry in dark and under UV-C and UV-VIS irradiation
Facilitated Electron Hopping in Nanolayer Oxygen-Insensitive Glucose Biosensor for Application in a Complex Matrix
No full textElectrochemical experimental evidence of facilitated electron transfer in a sub-micrometer biosensor is presented. Layer-by-layer self-assembled deposition provides the unique advantage to specifically control the thickness of the biosensors, allowing an oxygen-insensitive device with a film thickness of 70 nanometers to be obtained. The biosensor is based on a poly(allylamine) osmium redox mediator and glucose 1-oxidase. The immobilized enzyme contributes to the signal generation through the full biosensor thickness, with no loss of “active enzyme” in the outer layer of the biosensor through reaction with oxygen, as reported in the case of thick redox hydrogels. The application of the biosensor in complex matrices was approached with tests in wastewater. Encapsulation of the biosensor with Nafion® membrane ensured the protection of the enzyme molecules from the external environment, allowing the successful application of the sensor in a complex matrix
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Synthesis of a Cr-Cu surface alloy using a low-energy high-current electron beam
Full text linkA Cr-Cu surface alloy is synthesized using successive operations of Cr film deposition followed by mixing in a melted phase with the Cu substrate by a low-energy, high-current electron beam (LEHCEB). The parameters of LEHCEB are as follows: electron energy 20–30 keV and pulse duration 2–4 μs. Depending on the LEHCEB energy density, the concentration of Cr in the alloy is in the range from 60 to 20 at.%. The alloy microstructure has been analyzed, and its morphology is shown to represent nanosized chromium particles measuring 10–30 nm uniformly distributed in the copper matrix. The synthesized Cr-Cu surface alloys demonstrate a more than a factor of 3 a decrease in wear coefficient, which is nearly as low as the wear coefficient of Cr coatings. Some defects such as networks of cracks and pores, are observed in the lengthy regions of chromium. They are attributed to the tensile thermal stresses taking place during solidified melt cooling due to a large difference between the thermal expansion coefficients of copper and chromium
Modeling and First Characterization of Broad-Spectrum Vibration Rejection of Frequency Modulated Gyroscopes
Full text linkThe work presents a detailed modeling and the first-ever characterization of a frequency modulated (FM) yaw gyroscope in presence of vibrations from low frequency (30 Hz), through the main modes, and up to 40 kHz. The gyroscope two in-plane axes (around 25 kHz) are operated under a Lissajous trajectory (70 Hz period) by an integrated circuit (IC) including oscillators, frequency digitization, and digital demodulation stages. In presence of 2-gpk-pk vibrations, no effects are visible across the spectrum apart from the region including the modes. In this range, as predicted by theory, for each axis no effect is observed for accelerations at the axis resonance (< 0.1 dps/g), but a huge effect (tens of dps/g) is visible for accelerations at an offset frequency from resonance corresponding to the mode split
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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